1 / 67

Technician License Course Chapter 5 Amateur Radio Equipment

Technician License Course Chapter 5 Amateur Radio Equipment. Lesson Plan Module 12: Power Supplies and Batteries & RF Interference (RFI). Power Supplies. Most modern radio equipment runs from 12 volts DC. Household current is 120 volts AC.

norman-bradford
Download Presentation

Technician License Course Chapter 5 Amateur Radio Equipment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Technician License CourseChapter 5Amateur Radio Equipment Lesson Plan Module 12: Power Supplies and Batteries & RF Interference (RFI)

  2. Power Supplies • Most modern radio equipment runs from 12 volts DC. • Household current is 120 volts AC. • Power supplies convert 120 volts AC to 12 volts DC. • 13.8 volts DC is the common voltage you will see. • This is the charging voltage for motorized vehicles.

  3. Types of Power Supplies Linear: Switching: Electronics instead of transformers Light weight and small Not as robust Less expensive • Transformers • Heavy (physically) • Heavy duty current • Expensive

  4. Power Supply RatingsVoltage and Current • Continuous duty – how much current can be supplied over the long term. • Intermittent duty – how much surge current can be supplied over the short term. • Regulation – how well the power supply can handle rapid current changes, and keep the voltage constant.

  5. Mobile Power Wiring Safety • Special requirements for safe car wiring: • Fuse both positive and negative leads. • Connect radio’s negative lead to where the battery ground connection is made. • Use grommets or protective sleeves to prevent wire chafing. • Don’t assume all metal in the car is grounded; modern cars are as much plastic as metal. • Car batteries hold lots of energy – shorting a battery could cause a fire.

  6. Mobile Power Wiring • Use wiring of sufficient gauge. • Too small wire can lead to excessive voltage drop. • Mobile Noise • Alternator whine – high pitched noise that varies with engine speed. • Ignition noise – raspy or popping noise that also varies with engine speed. • There are filters that can help.

  7. Batteries • Create current through a chemical reaction. • Made up of individual cells (approximately 1.5 volts per cell) connected in series or parallel. • Battery types. • Disposable. • Rechargeable. • Storage. • Power capabilities rated in Ampere-hours. • Amps X time.

  8. Common Battery Types • Carbon Zinc 1.5V per cell Non rechargeable • Alkaline 1.5V per cell Non rechargeable • Lithium Coin 3.0 – 3.3 V Non rechargeable • Nickel Cadmium 1.2V per cell Rechargeable • NiMH 1.2v per cell Rechargeable • Lithium Ion 3.3 - 3.6V Rechargeable • Lead Acid 2 V per cell Rechargeable

  9. Battery Charging • Some batteries can be recharged, some cannot. • Use the proper charger for the battery being charged. • NiCad, NiMH, L-ion. • Batteries will wear out over time. • Best if batteries are maintained fully charged. • Over-charging will cause heating and could damage the battery.

  10. Storage Batteries • Some batteries (lead-acid) will release toxic fumes during charging so require ventilation. • Hydrogen gas is explosive • Contain sulfuric acid • Car batteries hold lots of energy – shorting a battery could cause a fire or explosion.

  11. Handheld Transceivers • Battery packs – packages of several individual rechargeable batteries connected together. • NiCad (nickel-cadmium) • NiMH (nickel-metal hydride) • Li-ion (lithium-ion) • For emergencies, have a battery pack that can use disposable batteries (AA size)

  12. Which is a good reason to use a regulated power supply for communications equipment? (T4A03) • A. It prevents voltage fluctuations from reaching sensitive circuits • B. A regulated power supply has FCC approval • C. A fuse or circuit breaker regulates the power • D. Power consumption is independent of load

  13. Which is a good reason to use a regulated power supply for communications equipment? (T4A03) • A. It prevents voltage fluctuations from reaching sensitive circuits • B. A regulated power supply has FCC approval • C. A fuse or circuit breaker regulates the power • D. Power consumption is independent of load

  14. What is the source of a high-pitched whine that varies with engine speed in a mobile transceiver’s receive audio? (T4A10) • A. The ignition system • B. The alternator • C. The electric fuel pump • D Anti-lock braking system controllers

  15. What is the source of a high-pitched whine that varies with engine speed in a mobile transceiver’s receive audio? (T4A10) • A. The ignition system • B. The alternator • C. The electric fuel pump • D Anti-lock braking system controllers

  16. Where should a mobile transceiver’s power negative connection be made? (T4A11) • A. At the battery or engine block ground strap • B. At the antenna mount • C. To any metal part of the vehicle • D. Through the transceiver’s mounting bracket

  17. Where should a mobile transceiver’s power negative connection be made? (T4A11) • A. At the battery or engine block ground strap • B. At the antenna mount • C. To any metal part of the vehicle • D. Through the transceiver’s mounting bracket

  18. How much voltage does a mobile transceiver usually require? (T5A06) • A. About 12 volts • B. About 30 volts • C. About 120 volts • D. About 240 volts

  19. How much voltage does a mobile transceiver usually require? (T5A06) • A. About 12 volts • B. About 30 volts • C. About 120 volts • D. About 240 volts

  20. What is the nominal voltage of a fully charged nickel-cadmium cell? (T6A10) • A. 1.0 volts • B. 1.2 volts • C. 1.5 volts • D. 2.2 volts

  21. What is the nominal voltage of a fully charged nickel-cadmium cell? (T6A10) • A. 1.0 volts • B. 1.2 volts • C. 1.5 volts • D. 2.2 volts

  22. Which battery type is not rechargeable? (T6A11) • A. Nickel-cadmium • B. Carbon-zinc • C. Lead-acid • D. Lithium-ion

  23. Which battery type is not rechargeable? (T6A11) • A. Nickel-cadmium • B. Carbon-zinc • C. Lead-acid • D. Lithium-ion

  24. What type of circuit controls the amount of voltage from a power supply? (T6D05) • A. Regulator • B. Oscillator • C. Filter • D. Phase inverter

  25. What type of circuit controls the amount of voltage from a power supply? (T6D05) • A. Regulator • B. Oscillator • C. Filter • D. Phase inverter

  26. What could be happening if another operator reports a variable high-pitched whine on the audio from your mobile transmitter? (T7B09) • A. Your microphone is picking up noise from an open window • B. You have the volume on your receiver set too high • C. You need to adjust your squelch control • D. Noise on the vehicle’s electrical system is being transmitted along with your speech audio

  27. What could be happening if another operator reports a variable high-pitched whine on the audio from your mobile transmitter? (T7B09) • A. Your microphone is picking up noise from an open window • B. You have the volume on your receiver set too high • C. You need to adjust your squelch control • D. Noise on the vehicle’s electrical system is being transmitted along with your speech audio

  28. What is one way to recharge a 12-volt lead-acid station battery if the commercial power is out? (T0A08) • A. Cool the battery in ice for several hours • B. Add acid to the battery • C. Connect the battery to a car’s battery and run the engine • D. All of these choices are correct

  29. What is one way to recharge a 12-volt lead-acid station battery if the commercial power is out? (T0A08) • A. Cool the battery in ice for several hours • B. Add acid to the battery • C. Connect the battery to a car’s battery and run the engine • D. All of these choices are correct

  30. What kind of hazard is presented by a conventional 12-volt storage battery? (T0A09) • A. It emits ozone which can be harmful to the atmosphere • B. Shock hazard due to high voltage • C. Explosive gas can collect if not properly vented • D. All of these choices are correct

  31. What kind of hazard is presented by a conventional 12-volt storage battery? (T0A09) • A. It emits ozone which can be harmful to the atmosphere • B. Shock hazard due to high voltage • C. Explosive gas can collect if not properly vented • D. All of these choices are correct

  32. What can happen if a lead-acid storage battery is charged or discharged too quickly? (T0A10) • A. The battery could overheat and give off flammable gas or explode • B. The voltage can become reversed • C. The “memory effect” will reduce the capacity of the battery • D. All of these choices are correct

  33. What can happen if a lead-acid storage battery is charged or discharged too quickly? (T0A10) • A. The battery could overheat and give off flammable gas or explode • B. The voltage can become reversed • C. The “memory effect” will reduce the capacity of the battery • D. All of these choices are correct

  34. Radio Frequency Interference (RFI) • Unwanted, unintentional signals from some electronic device that interferes with radio wave reception. • You can help prevent creating RFI by operating your transmitting equipment properly.

  35. RFI Mitigation • Filters • Filters attenuate (reduce) interfering signals – but do not totally eliminate them. • High-pass – generally on the receive side. • Passes higher frequencies, reduces lower frequencies. • Low-pass – generally on the transmit side. • Passes lower frequencies, reduces higher frequencies.

  36. RFI Mitigation • Filters • Band-pass – used within most radio equipment. • Passes a specific range of frequencies, and rejects all others. • Band-reject – notches out a range of frequencies, and passes others. • Ferrite chokes can block unwanted RF.

  37. Types of RFI • Direct Detection – offending signals get into the electronics circuits to cause interference. • Fundamental Overload – a strong signal that overwhelms the weaker, wanted signal. • Harmonics – even number multiples of the wanted signal that cause interference. • Spurious Emissions – unwanted emissions from a radio or electronic equipment.

  38. Cable TV Interference • Usually the result of broken shielding somewhere in the cable. • Loose connections. • Broken connections. • Corroded connections. • Usually solved by proper cable maintenance by cable supplier. • If the subscriber is a legitimate subscriber.

  39. Noise Sources • Electrical arcs (motors, thermostats, electric fences, neon signs). • Power lines. • Motor vehicle ignitions or alternators. • Switching power supplies. • Computers, networks, and TV sets.

  40. Dealing with RFI • Make sure you operate your equipment properly. • Eliminate interference in your own home first.

  41. Dealing with RFI • Take interference complaints seriously. • Make sure that you’re really not the cause (demonstrate that you don’t interfere within your own home). • Offer to help eliminate the RFI, even if you are not at fault. • Consult ARRL RFI Resources for help and assistance.

  42. What the Rules Say • RFI from and to unlicensed devices is the responsibility of the users of such devices • Bottom line – If your station is operating properly, you are protected against interference complaints • BUT – Be a good neighbor because they may (probably) not be familiar with Part 15 rules and regulations

  43. Where must a filter be installed to reduce harmonic emissions? (T4A04) • A. Between the transmitter and the antenna • B. Between the receiver and the transmitter • C. At the station power supply • D. At the microphone

  44. Where must a filter be installed to reduce harmonic emissions? (T4A04) • A. Between the transmitter and the antenna • B. Between the receiver and the transmitter • C. At the station power supply • D. At the microphone

  45. What type of filter should be connected to a TV receiver as the first step in trying to prevent RF overload from a nearby 2 meter transmitter? (T4A05) • A. Low-pass filter • B. High-pass filter • C. Band-pass filter • D. Band-reject filter

  46. What type of filter should be connected to a TV receiver as the first step in trying to prevent RF overload from a nearby 2 meter transmitter? (T4A05) • A. Low-pass filter • B. High-pass filter • C. Band-pass filter • D. Band-reject filter

  47. Which would you use to reduce RF current flowing on the shield of an audio cable? (T4A09) • A. Band-pass filter • B. Low-pass filter • C. Preamplifier • D. Ferrite choke

  48. Which would you use to reduce RF current flowing on the shield of an audio cable? (T4A09) • A. Band-pass filter • B. Low-pass filter • C. Preamplifier • D. Ferrite choke

  49. What is meant by fundamental overload in reference to a receiver? (T7B02) • A. To much voltage from the power supply • B. Too much current from the power supply • C. Interference caused by very strong signals • D. Interference caused by turning the volume up too high

  50. What is meant by fundamental overload in reference to a receiver? (T7B02) • A. To much voltage from the power supply • B. Too much current from the power supply • C. Interference caused by very strong signals • D. Interference caused by turning the volume up too high

More Related